Statistics Online Exam Help Answers

Statistics Online Exam Help Answers

Q1. A sample is selected from a population with m = 80, and a treatment is administered to the sample. If the sample variance is s2 = 20, which set of sample characteristics is most likely to lead to a decision that there is a significant treatment effect?

M = 85 for a sample of n = 25

M = 85 for a sample of n = 100

M = 90 for a sample of n = 25

M = 90 for a sample of n = 100

Q2. If a researcher reports a t statistic with df = 18, how many individual subjects participated in the experiment?

n = 17

n = 18

n = 19

cannot be determined from the information given

Q3. What t values define the critical region for a regular two-tailed test using a sample of n = 25 scores and an alpha level of .05?

t = ±1.711

t = ±1.708

t = ±2.064

t = ±2.060

Q4. A sample of n = 25 scores produces a t statistic of t = -2.06. If the researcher is using a two-tailed test with a = .05, the correct statistical decision is ____.

The researcher can reject the null hypothesis with a = .05 but not with a = .01.

The researcher can reject the null hypothesis with either a = .05 or a = .01.

The researcher must fail to reject the null hypothesis with either a = .05 or a = .01.

It is impossible to make a decision about H0 without more information.

Q5. Two samples from the same population both have n = 10 scores with M = 45. If t statistics are computed for these two samples, then ____.

the two t statistics will be identical

the sample with the larger variance will produce the larger t statistic

the sample with the smaller variance will produce the larger t statistic

There is no way to predict the relationship between the two t statistics.

Q6. Which of the following research situations is most likely to use an independent-measures design?

Evaluate the effectiveness of a diet program by measuring how much weight is lost during 4 weeks of dieting.

Evaluate the effectiveness of a cholesterol medication by comparing cholesterol levels before and after the medication.

Evaluate the difference in verbal skills between 3-year-old girls and 3-year-old boys.

Evaluate the development of verbal skills between age 2 and age 3 for a sample of girls.

Q7. What is the estimated standard error for the independent-measures t statistic for the following two samples? Sample 1: n = 4 with SS = 100. Sample 2: n = 8 with SS = 140.

3

9

24

242

Q8. Which of the following sets of sample data would produce the largest value for an independent-measures t statistic. Assume that n = 10 for all samples. Note: You should not need to do any serious calculations to answer this question

First sample: M = 30 and SS = 10. Second Sample: M = 35 and SS = 10

First sample: M = 30 and SS = 10. Second Sample: M = 50 and SS = 10

First sample: M = 30 and SS = 50. Second Sample: M = 35 and SS = 50

First sample: M = 30 and SS = 50. Second Sample: M = 50 and SS = 50

Q9. An independent-measures research study uses two samples, each with n = 10, to compare two treatments. If the results are evaluated with a t statistic using a two-tailed test with a = .05, then the critical region would have boundaries of ____.

t = ±2.262

t = ±2.101

t = ±2.093

t = ±2.086

Q10. An independent-measures research study uses two samples, each with n = 8 participants. If the data produce a t statistic of t = 2.10, then which of the following is the correct decision for a two-tailed hypothesis test?

Reject the null hypothesis with a = .05 but fail to reject with a = .01.

Reject the null hypothesis with either a = .05 or a = .01.

Fail to reject the null hypothesis with either a = .05 or a = .01.

cannot answer without additional information

Q11. An independent-measures experiment uses two samples with n = 7 in each to compare two experimental treatments. The t statistic from this experiment will have degrees of freedom equal to ____.

12

6

13

9

Q12. For which of the following situations would a repeated-measures research design be appropriate?

comparing verbal skills for girls versus boys at age 3

comparing pain tolerance before and after taking a new pain medication

comparing self-esteem for students who participate in school athletics versus those who do not

comparing problem solving skills for science majors versus art majors at a college

Q13. A researcher reports a t statistic with df = 24 from a repeated-measures research study. How many subjects participated in the study?

n = 11

n = 13

n = 23

n = 25

Q14. With a = .05 and a sample of n = 12 subjects in a repeated-measures experiment, the two-tailed critical region for the t statistic has boundaries of ____.

t = ±2.228

t = ±1.812

t = ±1.796

t = ±2.201

Q15. A major concern with a repeated-measures study is the possibility that ____.

you will obtain negative values for the difference scores

the results will be influenced by order effects

the mean difference is due to individual differences rather than treatment differences

All of the other options are major concerns.

Q16. A researcher plans to conduct a research study comparing two treatment conditions with a total of 20 participants. Which of the following designs would produce 20 scores in each treatment?

An independent-measures design

A repeated-measures design

A matched-subjects design

All of the other options would produce 20 scores in each treatment.

Q17. The following data were obtained from a repeated-measures research study. What is the value of MD for these data?

3

3.5

4

4.5

Q18. A matched-subjects study and an independent-measures study both produced a t statistic with df = 10. How many individuals participated in each study?

11 for matched-subjects and 11 for independent-measures

11 for matched-subjects and 12 for independent-measures

12 for matched-subjects and 12 for independent-measures

22 for matched-subjects and 12 for independent-measures

Q19. A repeated-measures study comparing two treatments with a sample of n = 4 participants produces MD = 3 with SS = 48 for the set of difference scores. What is the repeated-measures t statistic for these data?

3/3 = 1.73

3/2 = 1.50

3/4 = 0.75

3/16 = 0.19

Q20. A research report describing the results from a repeated-measures study states that the data show no significant difference between the two treatments, t(10) = 1.65, p > .05. Based on this report, how many individuals participated in the research study?

9

10

11

12

Q21. An independent-measures study has one sample with n = 6 and a second sample with n = 8 to compare two experimental treatments. What is the df value for the t statistic for this study?

7

12

13

14

Q22. An independent-measures study comparing two treatment conditions produces a t statistic with df = 18. If the two samples are the same size, how many participants were in each of the samples?

9

10

19

20

Q23. An independent-measures research study uses two samples, each with n = 15 participants. If the data produce a t statistic of t = 2.760, which of the following is the correct decision for a two-tailed hypothesis test?

Reject the null hypothesis with α = .05 but fail to reject with α = .01

Reject the null hypothesis with either α = .05 or α = .01

Fail to reject the null hypothesis with either α = .05 or α = .01

Cannot answer without additional information

Q24. If all other factors are held constant, increasing the sample size will ____.

increase the standard error

decrease the width of the confidence interval

increase the width of the confidence interval

None of the other 3 choices is correct.

Q25. Which combination of factors would definitely reduce the width of a confidence interval?

use a larger sample and increase the level of confidence

use a smaller sample and increase the level of confidence

use a larger sample and decrease the level of confidence

use a smaller sample and decrease the level of confidence

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